This invention concerns a frame for the support of articles which are to be treated by high voltage glow discharge in a receptacle, capable of being connected with a conductor which is carried in the receptacle with insulation.
In the treatment of articles by means of high voltage glow discharges for the purpose of nitride hardening, metallizing, annealing, hardening, carburizing, decarburizing, or the like, of the articles, they are set or hung in a receptacle and are in a circuit as cathode in the case of the use of direct current, and partially as cathode in the case of the use of alternating or polyphase alternating current, while the receptacle correspondingly has the other polarity. However, in this case, the charging is often time-consuming and difficult, particularly when the articles are elongated, such as crankshafts, especially those having partial centers of gravity, which cannot be connected by a straight line, because these elongated articles tend to distort with the heating which is effected during the glow discharge, if they are not hung in such a manner, that bending stresses are excluded. However, the later is difficult to accomplish and prevents an automatic charging of the receptacle.
The treatment of workpieces by means of glow discharge in itself has been well known for a long period of time. In this context see U.S. Pat. Nos. 3,846,574, 3,914,575, and particularly U.S. Pat. No. 3,865,451. The latter patent concerns a suspension device for the suspension of a workpiece and its function is thus similar to the object of the present application. The introduction to the description states that if direct current is used, the workpieces are cathodes in the circuit and the receptacle the anode, while in the case of alternating current, they are cathodes part of the time only. Obviously, the workpieces are heated by ion bombardment and treated in this manner. The cathodic glow light surround the entire surface of the workpiece and naturally also its suspension. Voltages and currents must be chosen at least high enough so that the cathodic glow light covers the entire surface of the workpieces; this, however, depends on the dimensions of the receptacle, the weight of the workpieces and the pressure prevailing in the receptacle. Accordingly, currents and voltages, for example, between a few volts and 1000 volts, between a few amperes and a 1000 amperes, or more, may be selected, depending on requirements.